removal of metals by phytoremediation
TRANSCRIPT
What is bioremediation?
• Bioremediation is a treatment process that uses naturally occurring microorganisms (yeast, fungi, or bacteria) to break down, or degrade, hazardous substances into less toxic or nontoxic substances.
• Microorganisms, just like humans, eat and digest organic substances for nutrients and energy.
• In chemical terms, "organic" compounds are those that contain carbon and hydrogen atoms.
• microorganisms can digest organic substances such as fuels or solvents that are hazardous to humans.
• What is phytoremediation?
• Phytoremediation can be defined as the use of green plants to remove pollutants from the environment or to render them harmless
• Phytoremediation is a form of bioremediation and applies to all chemical or physical processes that involve plants for degrading or immobilizing contaminants in soil and ground water.
• “Phyton“ = Plant (in greek)• “Remediare“ = To remedy (in latin).
Types of phytoremediation
Six main types
They are……..
Phytoremediation
Types of Phytoremediation
Phytoaccumulatin
Phytodegradation
Phytostabilization
Phytovolatilization
Rhizodegradation
Rhizofiltration
Biopump grown
Ni Au Cu Pd2+ 2+2++
The phytoextraction operationChemicals
addedPlant
material harvested and burnt to
produce bio-ore
Bio-ore smelted
Bio-ore landfilled
Phytomining Phytoremediation
Phytostabilization
• Phytostabilization is the use of plants to stabilize the soil matrix itself and immobilize the contaminant from future
migration
• Plants control pH, soil gases, and redox conditions in soil to immobilize contaminants.
• Humification of some organic compounds is expected.
• Phytovolatilization• Plants take up volatile
compounds through their roots, and transpire the same compounds, or their metabolites, through the leaves, thereby releasing them into the atmosphere
• .
• Phytodegradation• Contaminants are taken up
into the plant tissues where they are metabolized, or biotransformed.
• Where the transformation takes place depends on the type of plant, and can occur in roots, stem or leaves.
• Phytoextraction – plant removal of:– water– nitrates, phosphates– heavy-metals– some organic nasties
• Phytodegradation and stabilisation enhanced by:– soil aeration– plant exudates– soil microbiota stimulated
by plant exudates
Water and metals outof the soil -
Phytoextraction
Sugars and organic material into the soil -
Phytodegradation/stabilisation
BiopumpsBiopumps
• Rhizodegradation• It also called phytostimulation,
rhizosphere biodegradation, or plant-assisted bioremediation /degradation, is the breakdown of contaminants in the soil through microbial activity that is enhanced by the presence of the rhizosphere.
• Microorganisms (yeast, fungi, and/or bacteria) consume and degrade or transform organic substances for use as nutrient substances.
• Rhizofiltration• It is the adsorption or
precipitation of contaminants onto plant roots or the absorption of contaminants into the roots when contaminants are in solution surrounding the root zone.
• The plants are raised in greenhouses hydroponically (with their roots in water rather than in soil).
Overview of Phytoremediation
Mechanisms for Organic and Inorganic
Sources of heavy metal in the environment
Municipal and Industrial wasteSediment from wastewater treatment plant
Textiles Waste Pesticides
AtmospherePrimary pollutants (NOx,VOCs)Secondary pollutants (oxidants, fineparticulates
Intensive agriculture
Industrialization Urbanization Waste Water
Solid Waste
Exhaust gases
Agrochemicals
Rapid development
Soil Plant
Ag
ro-p
rod
uct
s
Water
Environment
Development vs Environment & Health
Approximately 400 plant species from at least 45 plant families have been reported to hyperaccumulate metals
Plant species………….of Phytoremediation
Water Hyacinth in Sewage Discharge Ponds• Due to the growth of water hyacinth, excess nutrients in the water column
are removed.
• Heavy metals in the sewage water is also taken up by water hyacinth.
• This is most essential aspect of sewage water treatment, which requires no chemicals or, electrical energy.
• Heavy metals cause many health hazards to human kind such as cancer, kidney disorder, hypertension, hormone imbalance (which has severe consequence on human reproductive mechanism), nervous disorder, etc.
• Under conventional treatment procedure, organic manure is produced before removing heavy metals
• Two problems are solved in a single step:
• Excess nutrients such as phosphorus and nitrate are removed
• Toxic heavy metals are also removed from entering the ecosystem.
Phytoremediation of mixed-contaminated soil using the hyperaccumulator plant Alyssum lesbiacum: Evidence of histidine as a measure of phytoextractable nickel
Alyssum lesbiacumEffects of Ni addition on shoot dry weight (a) and the concentration of Ni in the shoots (b). The concentration of Ni was determined with ICP-AES
Phytostabilization of Mine Tailings in Arid and Semiarid EnvironmentsAn Emerging Remediation Technology
Phytoremediation of Hexavalent Chromium Polluted Soil UsingPterocarpus indicus and Jatropha curcas
• Phytoremediation of chromium polluted soil using local and potential plants poses a number of unique interlink advantages particularly for Surabaya as well as other big cities in Indonesia
• Pterocarpus indicus and Jatropha curcas were able to remediate hexavalent chromium polluted soil of less than 90 mg KgG1.
• Jatropha was planted in hexavalent chromium polluted soil because Jatropha could remediate higher concentration than Pterocarpus
Pterocarpus indicus Jatropha curcas
Cont….
Metal Phytoremediation potential of
Rhizophora mucronata
Cont………..
Improve Phytoremediation using Genetic Engineering.
• Introduce genes encoding transport proteins.
• IRT1 iron transporter• MRP1 Mg-ATPase transporter• High affinity Zn transporter from
Thalassiosira weissflogiiIntroduce genes encoding metal-sequestering proteins or peptides.
• Phytochelatins (e.g., cad1)• Metallothioneins• Introduce genes to enhance
metal transport into roots, and from roots to other plant biomass.
• Genes encoding metal chelators
• Introduce genes to change the oxidation state of metals.
• mercuric reductases• selenium methylation
enzymes• Organics• Introduce genes encoding key
biodegradative enzymes (plant and microbial origin).
• Laccases• Dehalogenases
.
Metals
Before….….. After
Phytoremediation Advantages:
- Low cost
- Well suited for use at very large field sites
- Transfer is faster than natural attenuation
- High public acceptance
- Fewer air and water emissions
- Soils remain in place and are usable following treatment
- Compatible with engineered technologies
Phytoremediation Applications
Phytoremediation Limitations - Long duration of time for remediation
- Not all compounds are susceptible to rapid and complete degradation
- High concentrations of hazardous materials can be toxic to plants
- Effective only for moderately hydrophobic contaminants
- Toxicity and bioavailability of degradation products is not known
- Potential for contaminants to enter food chain through animal consumption
- Hyperaccumulators are often slow growers
- Need to dispose plant biomass
Thank you